The glycemic response to the administration of modified corn starch and amylopectin-compared with the unmodified form has consistently shown a lesser glycemic response to the modified forms of glycogen. The accumulated evidence convincingly points to a beneficial effect on kidney function when the blood glucose level is maintained with corn starch. If long-term observations support this impression, corn starch therapy will have a significant long-term impact on prognosis of type I glycogen storage disease (GSD). This study is designed to determine the rate of glucose production by the liver in individuals with type I glycogenosis. Patients with type Ill GSD were studied as control GSD subjects. The calculations of the latest data is not yet complete. The pharmacokinetics and the effect of dichloracetate in patients with type Ia glycogenosis were studied in 3 patients.